Background. “Cẩm” rice bran has been considered a waste product; however, it possesses rich bioactive compounds. These compounds could be utilized to make value-added products, using microwave-assisted extraction.

Materials and methods. This study aimed to investigate and establish the kinetic extraction for “Cẩm” rice bran under different conditions of microwave-assisted extraction. Five levels of microwave power (90, 150, 300, 600, and 800 W) were used for extraction at a time range from 0 to 30 minutes. The extraction yield (%) and total phenolic compound (mg gallic acid equivalent per g, mgGAE/g) were determined. The experimental data were fitted with five empirical models to find the best fit model.

Results. The power of irradiation greatly influenced the extraction yield and phenolic compounds in rice bran extract. The fast rate of extraction was found at the initial stage (after 5 minutes of extraction), then remained unchanged or slightly declined. Among the five models, the first-order model showed the best fit between the actual and predicted data.

Conclusions. Based on the extraction rate constant from the first-order model, 500 W was considered the appropriate power level for extracting polyphenol from rice bran with a high yield of extraction and total polyphenol content. These conditions could be further optimized and upscaled for use in the food industry.

Keyword: microwave-assisted extraction, rice bran, polyphenol, antioxidant, waste